Preparation method of nano-graphene composite concrete water-reducing powder and composition thereof

Abstract

The application discloses a preparation method of a nano-graphene composite concrete water-reducing powder and a composition thereof, adopts 1-3 layers of few-layer graphene, is dispersed through ultrasonic-shearing-dispersant threefold dispersion, is in-situ compounded with a high-water-reducing polycarboxylic acid mother liquor, and is prepared into a high-dispersion powder with an agglomeration rate of ≤3%, a water content of ≤2% and a water-reducing rate of ≥35% through environment-friendly spray drying; and the 28d compressive strength ratio after compounding is ≥160%, and the impermeability is ≥P12. The application solves the problems of graphene agglomeration, inconvenient liquid storage and transportation, poor performance synergy, and non-environment-friendly process, and is suitable for high-strength and high-durability concrete engineering.

Description

Technical Field

[0001] This invention belongs to the field of concrete admixture technology, specifically relating to a method for preparing a nano-graphene highly dispersed composite polycarboxylate superplasticizer and its composition, which is particularly suitable for C50–C80 high-strength concrete, marine concrete, tunnels, hydraulic engineering, and high impermeability and high durability projects. Background Technology

[0002] Polycarboxylate superplasticizers are core materials for high-performance concrete, and nano-graphene can significantly improve concrete strength, impermeability, and durability. However, existing technologies suffer from five major industry pain points: (1) Graphene is extremely prone to agglomeration and cannot be stabilized by conventional dispersion methods; (2) The products are mostly liquid, which is inconvenient to store and transport and easily deteriorates; (3) The powder process is prone to secondary agglomeration, resulting in poor performance synergy; (4) Some processes use organic solvents, which are not environmentally friendly; (5) Water reduction, enhancement, impermeability, retardation and slump protection cannot be integrated and coordinated.

[0003] No existing technology discloses the complete technical solution of the present invention, which combines ultrasonic-shear-dispersant triple dispersion, in-situ compounding, environmentally friendly spray drying, and functional compounding. The present invention possesses outstanding novelty and inventiveness. Summary of the Invention

[0004] Technical problems to be solved (1) Solve the problems of severe graphene agglomeration and unstable dispersion; (2) It achieves powder form, which facilitates storage and transportation and extends shelf life; (3) Achieve synergistic effects of water reduction, enhancement, impermeability, retardation, slump retention, and air entrainment; (4) Provide a green process that is all-aqueous, solvent-free, low-energy, and industrially feasible; (5) Improve the flowability, moisture resistance and uniformity of powder.

[0005] 3.2 Technical Solution This invention employs a triple dispersion forced depolymerization + in-situ composite stabilization + medium-low temperature spray drying + multifunctional mineral synergy to achieve highly dispersed graphene, stable powder, and significantly improved performance.

[0006] 3.3 Beneficial Effects (1) Extremely stable dispersion: aggregation rate ≤3%, no stratification after 72 hours; (2) High water reduction rate: 35%–42%, far exceeding conventional products; (3) Strength and impermeability are outstanding: 28-day strength ratio ≥160%, impermeability ≥P12; (4) Excellent powder quality: moisture content ≤2%, good flowability, and no clumping; (5) Green and environmentally friendly: all-aqueous, VOC-free, safe and non-toxic; (6) Multifunctional and synergistic: One agent for multiple uses, suitable for demanding engineering projects; (7) Low cost and easy mass production: Graphene is used in small quantities and the process is stable.

[0007] 3.4 Outstanding inventiveness compared to existing technologies This invention has outstanding substantive features and significant progress compared with the prior art: 1. A triple forced depolymerization and dispersion system of ultrasound + high-speed shearing + polyether dispersant is adopted to fundamentally solve the industry problem of easy agglomeration and difficulty in stabilizing graphene in powder, achieving an agglomeration rate of ≤3% and no stratification after 72 hours; 2. In-situ composite rather than physical mixing is used to form a stable bond between graphene and polycarboxylic acid molecules, avoiding secondary agglomeration during spray drying, and achieving a water reduction rate of 35%–42%, far exceeding the 25% level of conventional powders; 3. Low-temperature spray drying at 180℃ / 80℃ is adopted, which is all-aqueous and free of organic solvents, making it green and environmentally friendly, while ensuring good powder flowability, low moisture content and no clumping; 4. The compound system achieves six functions in synergy: water reduction, reinforcement, impermeability, retardation, slump retention, and air entrainment. The 28-day strength ratio is ≥160%, and the impermeability is ≥P12. It can be directly used in high-durability projects such as C50–C80 high-strength concrete, marine engineering, and hydraulic engineering.

[0008] The combination and synergistic effect of the above technologies are not simply a superposition of conventional methods in this field, but have achieved unexpected technical results and have outstanding inventiveness. 4. Detailed Implementation Example 1 (Best Example) (1) Graphene 1.2% dispersion, ultrasonicated at 500W for 30min + sheared at 13000r / min for 10min, and 0.2% polyether dispersant was added; (2) Polyether monomer with a molecular weight of 2800, in a ratio of 28:10:1.2, synthesized at 42℃ for 1.5h; (3) Graphene: Mother liquor = 1:30 composite, add 3% retarder and 0.3% defoamer, stir at 35℃ for 30min; (4) Spray drying at 180℃ / 80℃ to obtain powder; (5) Grind the compounded ball mill according to the ratio of 15:7:4:2.5:0.6:0.15:0.1.

[0010] Performance: Water reduction rate 38%, agglomeration rate 2.5%, moisture content 1.8%, strength ratio 165%, impermeability P12, slump loss 12%. Example

[0011] Process fine-tuning, performance: water reduction rate 35%, agglomeration rate 2.8%, strength ratio 160%, impermeability P12.

[0012] Comparative Example 1 (commercially available powder) Water reduction rate 25%, strength ratio 115%, impermeability P8, prone to caking.

[0013] Comparative Example 2 (Simple Physical Mixture) The aggregation rate was 12%, the water reduction rate was 28%, and the performance was significantly reduced.

[0014] 5. Performance testing basis According to the test results of GB 8076-2008 "Concrete Admixtures", all the embodiments of the present invention far exceed the national standard, and the comparative examples are significantly inferior to the present invention, and the technical effect is not obvious.

[0015] 6. Novelty and Inventiveness This invention is a complete and original technical system, which is not a simple superposition of existing technologies. It achieves unexpected technical effects and has outstanding substantive features and significant progress.

Claims

1. A method for preparing a nano-graphene composite concrete water-reducing powder, characterized in that, The steps are as follows: (1) Add 1–3 layers of redox few-layer graphene with a sheet diameter of 80–150 nm to deionized water to prepare a pre-dispersion with a mass concentration of 0.8%–1.5%; The graphene dispersion with an agglomeration rate of ≤3% and no stratification after standing for 72 hours was prepared by ultrasonication at 400–600W for 25–40 min, high-speed shearing at 12000–15000r / min for 8–15 min, and the addition of 0.1%–0.3% polyether dispersant by weight of graphene. (2) Add methylalkenyl polyoxyethylene ether with a molecular weight of 2400–3600 and water to the reactor. After dissolving, add acrylic acid, sodium methacrylate and mercaptoacetic acid in a mass ratio of 28:10:1.

2. Heat to 40–45℃ and add 5%–10% ammonium persulfate aqueous solution dropwise for 1–1.5 h. Keep the reaction at this temperature for 1.5–2 h to obtain polycarboxylic acid mother liquor. (3) Add the graphene dispersion to the mother liquor at a ratio of graphene:mother liquor = 1:25–1:40, then add sodium gluconate and sodium citrate at a mass ratio of 1:1 and 2.5%–3.5% of total mass, and 0.2%–0.5% of total mass of organosilicon defoamer; The composite slurry was obtained by stirring at 30–35℃ and 400–600 r / min for 25–40 min. (4) The composite slurry is spray-dried at an inlet temperature of 170–190℃ and an outlet temperature of 75–85℃ to obtain a water-reducing powder with a mesh size of 150–325, a moisture content of ≤2%, a bulk density of 0.65–0.75 g / cm³, and a flowability of ≤10s.

2. The method according to claim 1, characterized in that, Step (4) The spray drying conditions are 180°C at the inlet and 80°C at the outlet.

3. A method for preparing a nano-graphene composite concrete water-reducing powder composition, characterized in that, The product comprises, by weight, 15 parts of the water-reducing powder as described in claims 1–2, 7 parts of grade I fly ash, 4 parts of ≥96% active silica fume, 2.5 parts of gypsum dihydrate, 0.6 parts of tartaric acid, 0.15 parts of rosin thermal polymer, and 0.1 parts of water-reducing and water-retaining agent; prepared by ball milling at a ball-to-material ratio of 4:1 for 40–60 min and mixing at 300 r / min for 20 min.

4. A nano-graphene composite concrete water-reducing powder, characterized in that: Prepared by any of the methods of claims 1–2, with a water reduction rate ≥35%, an agglomeration rate ≤3%, and a moisture content ≤2%.

5. A nano-graphene composite concrete water-reducing powder composition, characterized in that... It is prepared by the method described in claim 3, and has a 28-day compressive strength ratio ≥160%, impermeability ≥P12, and slump loss ≤15% over 1 hour.